Blasting initiator



Feb. 6, 1940. G. H. SMITH El" AL 2,139,301

\ BLASTING INITIATOR Filed Nov. 19, 1956 01719621 #5277271? Caz"!Z5.Vaz2 I Wmer INVENTOM ATTORNEY.

Patented Feb. 6, 1940 UNITED STATES-PATENT OFFICE BLASTING INITIATORGilbert H. Smith, Woodbury, and Carl B. Van Winter, Wenonah, N. J.,assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., acorporation of Delaware Application November 19, 1936, Serial No.111,582

13 Claims.

types, however, employ ignition compositions. In"

the case of the blasting cap the ignition composition serves to initiatea detonating base charge, whereas in the squib it is employed as theflameproducing base charge which ignites; the black powder.

Ignition compositions suitable for use in either electric detonators orelectric squibs should possess low uniform firing properties which canbe readily duplicated in manufacturing operations. For electric squibsthe ignition composition should possess, in addition to the low firingcurrent properties, the ability to develop a hot flame of considerableduration on combustion. This property is required since in wet coalmines it is often necessary to ignite moist pelleted powder. Althoughsome ignition compositions possess one or the other of these necessaryproperties, it is well recognized in the art that few materials areavailable which have all the required characteristics to the desireddegree.

/ The object of the present invention is a new and improved ignitioncomposition. A further object is such an ignition composition which issatisfactory with respect to low firing current and which produces a hotflame of considerable duration. A further object is a new and improvedelectric squib capable of igniting moist pelleted black powder. Furtherobjects will be apparent from the detailed description of our inventionwhich follows.

We have found that the foregoing objects may be accomplished byemploying an ignition composition comprising smokeless powder, orsmokeless powder and an oxidizing agent, preferably in the form of agrained loose charge, the smokeless powder being desirably ground. Wehave discovered further that the ignition properties are very desirablyimproved by incorporating therewith certain finely divided reductivefuels. For the purpose of our invention a greatjnumber of reductivefuels may be used, for example readily oxidizable, atmosphericallystable metals or metalloids, such as selenium, tellurium, zirconium,magnesium, aluminum and the like. Alloys as well as elementary metalsmay be employed, for example calcium silicide. Other readily oxidizable,atmospherically stable reductive fuels may be used in place of themetals, for

example, sulfur and the like.

In order to disclose the nature of our invention more clearly, referenceis made to the accompanying Table I, which illustrates preferred ex,-amples of ignition compositions in accordance with our invention.

Table I Composition Metal or Exam le e p Smokeless Oxidizing metanmdpowder agent Percent Percent Percent I 100- 0 0 II 20 (K0103) 0 5O 42(B302) 8 (OaSn) 50 47 (BaOz) 3 (s) 50 40 EBaOz) 10 (Se) 50 39 B802) 11(Zr) In addition to the oxidizing agents. indicated in the foregoingtable we may employ lead dioxide, potassium nitrate, barium nitrate andmany other oxidizing agents.

In order further to illustrate the nature of .our invention, referenceis made to the accompanying drawing which represents preferredembodiments thereof. It is understood, however, that this is done solelyby way of illustration and is not to be regarded as a limitation uponthe scope of our invention.

Referring generally to the drawing, Figure l is a vertical elevation ofan electric blasting cap, while Figures 2 and 3 are similar views ofclosed shell electric squibs. Corresponding parts of the differentfigures are represented by similar characters referred to in thefollowing description.

In the drawing the numeral 1 represents a 1 metal shell of any suitablematerial, such as aeld in position by the bridge plug 1 and the ahell isclosed by the waterproofing composition 3 and the usual sulfur seal 9.

Fi 1re 2 illustrates an electric squib'in accordance with our invention.The shell I contains the base charge 2 of suitable deflagratingmaterial, such as black powder. The base charge 2 is covered by a looseignition charge 4 in accordance with our invention, for example thecomposition IV of Table I.

Figure 3 illustrates an electric squib differing slightly inconstruction from that shown in Figure 2, in that a single base charge 4is employed. This base charge 4 may consist of any of the compositionsin accordance with our invention, for example the composition V of TableI.

The firing currents necessary to ignite squibs having the foregoingignition compositions range from 0.330 to 0.365 ampere, and due to thefact that the ignition compositions produce a hot flame of considerableduration the electric squibs in accordance with our invention arecapable of igniting moist black powder pellets. The compositionsdisclosed can be consistently reproduced in large scale manufacture togive initiators having a high degree of uniformity in ignitionproperties.

Although we prefer to employ the compositions of our invention asignitioncharges in electric squibs, either alone or as a-primary charge,they may be used in electric blasting initiators generally as ignitioncharges, as illustrated in Figure l or the drawing. Although we mayemploy our ignition compositions generally in electric blastinginitiators, we find them particularly advantageous when used in'closedshell electric squibs provided with a bridge wire of slow fusingproperties, as described and claimed in the copending application ofLawton. A. Burrows and Carl B.

Van Winter, Serial No. 111,581 filed November 19, 1936.

In the foregoing detailed description of our invention, it is apparentthat many variations can be made without departing from the spirit andscope thereof. We intend, therefore, to be limited only in accordancewith the following patent claims.

We claim:

1. An electric blasting initiator containing an ignition compositioncomprising smokelesspow der, an oxidizing agent, and at least one memberof the group of reductive fuels consisting of sulfur, calcium silicideand readily oxidizable, at-

mospherically stable metals and metalloids.

2-. A closed shell electric squib containing a loose ignitioncomposition comprising smokeless powder, an oxidizing agent, and atleast one member of the group of reductive fuels consisting of sulfur,calcium silicide and readily oxidizable, atmospherically stable metalsand metalloids.

3. A closed shell electric squi'bpontaining a loose ignition compositioncomprising smokeless powder, an oxidizing agent, and calcium silicide.

4. A closed shell electric squib containing a loose ignition compositioncomprising smokeless. powder, an oxidizing agent, and sulfur.

5. The electric squib of claim 2, wherein the reductive fuel isselenium.

6. The electric squib of claim 2, wherein the reductive fuel iszirconium.

'7. The electric squib of claim 2, wherein the oxidizing agent is bariumperoxide;

8. An electric blasting initiator containing an ignition compositionconsisting of smokeless powder and an oxidizing agent.

9. A closed shell electric squib containing a loose ignition compositionconsisting of smokeless powder and an oxidizing agent.

10 The electric squib according to claim 9, wher in the oxidizing agentis barium peroxide.

11. The electric squib according to claim 9,

wherein the oxidizing agent is potassium chlorate. 12. The electricsquib according to claim 9,

I wherein the oxidizing agent is potassium nitrate.

13. An electric blasting initiator containing an ignition compositionconsisting of groundsmokeless powder. 1.

GILBERT H. SMITH. CARL B. VAN WINTER.

